[test] Add test helper utilities for Vue node system testing

- Add nodeTestHelpers.ts with mock factories for widgets, nodes, and canvas
- Include mock utilities for VueNodeData, LiteGraph nodes, and canvas contexts
- Provide createBounds helper for spatial testing
- Foundation for comprehensive testing of Vue node system components

tests-ui/tests/helpers/nodeTestHelpers.ts

@@ -0,0 +1,76 @@
+// Simple mock objects for testing Vue node components
+export function createMockWidget(overrides: any = {}) {
+  return {
+    name: 'test_widget',
+    type: 'number',
+    value: 0,
+    options: {},
+    callback: null,
+    ...overrides
+  }
+}
+
+// Create mock VueNodeData for testing
+export function createMockVueNodeData(overrides: any = {}) {
+  return {
+    id: 'node-1',
+    type: 'TestNode',
+    title: 'Test Node',
+    mode: 0,
+    selected: false,
+    executing: false,
+    widgets: [],
+    inputs: [],
+    outputs: [],
+    ...overrides
+  }
+}
+
+// Create a mock canvas context for transform testing
+export function createMockCanvasContext() {
+  return {
+    canvas: {
+      width: 1280,
+      height: 720,
+      getBoundingClientRect: () => ({
+        left: 0,
+        top: 0,
+        width: 1280,
+        height: 720,
+        right: 1280,
+        bottom: 720,
+        x: 0,
+        y: 0
+      })
+    },
+    ds: {
+      offset: [0, 0],
+      scale: 1
+    }
+  }
+}
+
+// Helper to create bounds for spatial testing
+export function createBounds(
+  x: number,
+  y: number,
+  width: number,
+  height: number
+) {
+  return {
+    x,
+    y,
+    width,
+    height
+  }
+}
+
+// Helper to create a position
+export function createPosition(x: number, y: number) {
+  return { x, y }
+}
+
+// Helper to create a size
+export function createSize(width: number, height: number) {
+  return { width, height }
+}